Fixed-angle helical-gear hobber



1 1927. April 9 w. F. ZLMMERMANN FIXED ANGLE HELICAL GEAR HOBBER Filed Jan. 23. 1925 Sheets-Sheet l 1 E EN 192 April 19 w. F. ZIMMERMANN FIXED ANGLE HELICAL GEAR HOBBER Filed Jan. 23. 1925 4 Sheets-Sheet 2 l 27. Apr 19 9 w. F. ZIMMERMANN FIXED ANGLE HELIQAL GEAR HOBBER Filed Jan. 23. 1925 4 Sheets-Sheet 5 Suva/nto@ 1927. April 19 w. F. ZIMMERMANN FIXED NGLE HELICAL GEAR' HOBBER Filed Jan. 23. i925 Sheets-Sheet 4 @www Patented Apr. 19, 1927.

unirse stares ,l i 1,625,581 PATENT erica.

WLLIAM F. ZIMMERMANN, OF MAPLEWOOD, NEVI JERSEY, ASSIGNOR T GOULD 85 EBERI-IARDT, 0F NEARK, NEW JERSEY, A CQRPORATION OF NEW JERSEY.

v FIXED-ANGLE HELICAJ-GEAR vI-IOBIBER.

Application filed January rlhis invention is devoted to machines accommodating hobs ot different pitches and adjustable for hobbing helical (as distinguished trom spur) gears in various sizes and of various numbers of teeth and con- `torming to a predetermined base or helix angle of substantial magnitude, say about an eighth to a-'third` of a quadrant; the fundamental object-ive being to reconcile certain incompatible factors so as to provide a structure ot maximum rigidity, cutting-ability and accuracy, of minimum complexity and cost, and yet` siitliciently adaptable when installed to produce range ot gears satisfying all ordinary shop requirement-s. This objective, has been attained, in part through certain improvements over and reorganiza-A tions ot the mechanisms disclosed aswell in my United Stat-es Patent No. 1,472,767, as in m sendingan alications Serial No. 720 393 i l a 7 ytiled .lune Y16,. 1924, and No. 784,487 filed August 2?, 1924i, and in part, hv resorting to certain novel conceptions and characteristic combinations; all as set forth hereinafter.

Y For example, my Patent No. 1,472,767 illustrates a machine primarily suitable for cutting spur-gears ot a sii gie pitch and limited range otniirnhers of teeth, but in that machine the work-support is shi'table and the mounting ot the cutter spindle is incompatible with the use ot compound changegears for extending the range unless the balanced drive be nacriticed. ln my application No. '720,893, there is shown a machine ,for cutting spur-gears of different pitches and a wider range ot numbers of teeth, but again the work-support' is made shittable and the cutter spindle does not conform to my present invention in respect to providing a plus and minus incremental adjustmenttrom Ysubstantial. base-angle and furthermore the relation ot splined to iin-splined shaftsV is ditiierent. In my application No. 73h48?, the machine illustrated presents the st natural advantage of a non-shittable ,3 1 l vwork-supgort but, while it is primarily suitable for cutting spur-gears within the range ot in v atoresaid nat-ent.v it neither shows a combination Ywhich is simplified and yet is adjus'able to accommodate various conventional hobsY nor does it Vshow one compatible with a drive which is balanced and yet including compoundA change-gears tor. correlat-ing the ratios to yield thehelical effect;

23, 1925. serial No. 4,207.

all ot which would be essential in a machine satisfying the need for the present invention with its attendant specialadvantages.

What is meant by balanced drive by base-angle and by incidental angle, as used herein may be deined as follows: A balanced drive7 denotes a special relationship between the elements connecting the driven cutter spindle and the driven work spindle respectively with the common source of power; said relationship being such that neither branch presents more sources or" back-lash, such as pairs ot intermeshing vgear-teeth, than the other branch; thereby reducing disproportionsV in vibrations and minimizing the tendency to chatter under the intermittent releases of successive teeth from `the work. A base angle7 signiies the helical angleof the teeth at the pitch line of a tilted magnitude with respect to the axis of the helical gear the machine is correlated to produce, and by incidental angle is meant the requisite departure trom the base angle to compensate for the helical angle of the hob cutter and its magnitude is dependent upon the pitch diaineer and number ot threads of the cutter.

ln any machine, and especially in one for hobbing helical gears involving the mechanical problems existing where there is an intricate correlation of component motions, each Vreduction in the number et' individual paris contributes proportionally both to the sturdiness and tothe intrinsic accuracy of the machine, and these qualities are ot paramount importance where helical gears are to be accurately generated by a hobbing eii'ect; all of which is fully realized by those skilled in this special art.

The general objective oltnis invention is to accomplish a reorganization of a helicalgear hobb-er such that its stationary (aswell as itsmoving) elements will not only be reduced in number to the ininimunnbut'will be arranged in eftlcient mutual relations; all in such a manner that the machine will still exhibit the capacity needed by its users in order to meet the acual range of operations demanded yby the more prevalent conditions of shop usage. Considering the ultimate or terminal elements 'for driving the hob, tor' instance, their number should be as `te'w and their action should be as direct as possible, and yet they should provide adjustments in the angularity of the setting of thev hob) auch that ditlei'cnt e. rt hohe may' he infei changeahlv einplo '\ecl and helical yearn ot dillercnt pitchce: mar he cut; it heinel iinportant in all Such annular adjustments to maintain a proper relation hclneen the hoh and the work-axle such that the hoh uill not he displaced undul)v to one side or the other and so that the ttull eeneratiire` action ot the hob will he utilized in completing;` the proper contour ot the tooth.

lly so devising` the hohhcr thatA it4` in a structural sense. resolves the complete worle ing'Lang-le into a comparatively large hase-- ang-le (related primarily lo the helical gear) and into a comparatively small incidental angle (related prin'iarilv to the hoh) it he comes poesilile to achieve a rsinnpli'ication heretofore unknown in machines employing short h-ohs 'for generating helical genre. That is to Say, hv thun dillerentiating, it becomes feasible to discard the rather involved and round-about drive hert-itotore ne cessitated in singleehoh machines where the center ot swing; ot the hoh was at or near the intersecton hetiveen the axial planes ot the hob and the Werl: respectively, and, in lieu thereot', to resort to a fundamentally simple and immediate drive in which the center of Swing will he located, not at said intersection or midwayv the aliden'ay, hut at one end o'l the hoh-spindle; the extent ot the swine; in the new arrangement not heine' sutticient, inthe absence ol a re-mounting` ot the hoh, to yield a choice ot materiallv dit 'ferent hase angles hut heine' nevertheless adequate to accommodate all ot auch minor angles as mayY he incidental to a Suhetantial base angle ot' predetermined magnitude. This mechanical premise ot adhering1 to what may he regarded an a fixed hase angle and providing latitude With reapect to What maj-,fT he regarded as an incidental angle, opensl the wav in generating helieattirare` to the. use. dircctl)vv on the end of the hoh spindle, ot an angle `rear in a dual capacity, i. e., an a swivel-gear as well as a driving;- ggear: its mate heine; on (and its center ot swivel heine coaxial with) an olli-Set short croas-eha'tt A`e'cared directlyT to a main traue,- misaion shalt. While Such an arrangement would not (in the ahaence ot triuihlesonic nianipulatious or atruetural complicatioun) `vield a range et swing;- saitlicient to enahle the machine to he adjustahle to cut other than helical teeth hy reason ot the reaultant dis` placement ot the short hoh (the Shitt heine` proportional to the disproportionaily-varying` conine ot' the angle ot variation) it will nevertheless, atl'ord as much adjuetment an ma)Y he required tor the incidental ano'le'to compensate ter the diltlerent helix angles of conventional hohs and it ivill accoidinglv permit the cutting ot' helical gema ot, ditl'erent. pitches with the saine'hase angle ot helix, and it will also accommodate the employweasel nicht oi? aimple or double thread hobs; all through a drive ot fundamental ein'iplicitv. ot" tcw parte'A` and characterized hy directnenn ot action. lt is to he remembered, in this connectionl` that the length ot a hoh, which is a complex and cost-ly tool, is limited hv various considerationsg Well known by those skilled in the art and that, as a connequence. hohe. must he quite Short in length and hence the rcgrion ot the hoh available 'for cutting pui-pones ia contini-al rather clo.-, .l v lo the middle ot the hol), and turther, that middle region muet he hcpt quite near the ilit'elsca'tion ol the axial planes; oi the hoh and ot the hlanlt no as to avoid any neeixaaityv tor :in vv coneiderahle lateral reacttinal ot' the hoh on the cutter spindle. l`here tore, in a machine organi'fied under the principlcs stated, it will he autlicient (through the ott-set center arrangements) to provide a range ot' swing' ot any about 100 and to locate that rangi'e, at the region ot inclination determined hy the hase angle; any extension ot that range heine; surplusage in a` machine devoted to the hoohine' ot helical r(fears and which attains the adjustment tl'irough the oil-Set location of the center ot swing;-a and in which, througljh the directneas ot the drive and the tewness; ot the parts, there ie secured the t'recdom trom vibration and incipient chatter which is ot auch great consernience where helical gears arel to he generated hr the hohhing etliect. It may here he noted, tnrther` that this proposition renders it especially iteasihle to employ, an an improvement in detail. thatv Species; of swivel angle-gears known as a Worin and 7Wormnvheel with the resultant advantage that the drive will he steadier and helical nears ot a smoother tinissh and ot a contour conforming; with greater precision to the ideal may he generated. there the center ot swine is not ott-Set in the manner herein propoeed, i, c..y where it in mid 'ay the ende ot the spindle in the vicinity o'll the at'ore `Said intersection (as:` han heretotore heen the practice in helical-rear hohhers) it iS not icanihle to cniplo'vY or secure the Special advantagee ot a ivornl-wlncl drive at the cut ter-Spindle h v rcanon ol" the coniplications ol." the coiwentional round ahout drive.

lt tur! hcrmore the aim ot thin invention to merce the ahove noted improved iininfove menta with a hi'ilained--drive avalent yielding the helical ctlcct and to correlate that combination with a rcm'ganiyiation ol the maior haine-elements otthe machine which will avoid the hahitnal intervention ol a Work- Supportingr carriage hetn'een the hed and the ivorlesnpporting1 Spindle; this heine' accomplished by journaling that spindle directl)7 in the bed ot the machine near one end and so devising; and mounting the stanchion that it may he shifted as hereiir atter explained to provide the adjustmentino llll

` ness for various diameters of work. Among the advantages derived from the manner of mounting the spindle aietlst) by eliminating the carriage, the axis of the hob may be located closer to the slideways of the stanchion and the overhang is thus reduced and less vibration can occur in the hob; (2nd) the work-supporting spindle has a more solid support directly in the heavy casting of the within the easy reach of the attendant whether for cutting gears of larger or of w 1 L L I smail diameters; ancl (Lith) the fixed position of the spindle on the bed enables a t .larger worin-wheel to be afli'xed to its spindle and enables the. bed casting to be reinforced and made more rigid with the saine weight of'metal than -if clearances forthe travelV of the enclosed worin-wheel had to be provided.

To take advantage of the otherwise necessary inassiveness of the stanchion by utilizing it in a steadying capacity is likewise within the objective of this invention. The stanchion, which is virtually a part of the bed,vhas Vto be provided as a ysupport for lthe hob, and as the hob is necessarily Vlocated some distance from the plane of the bed, the stanchion must be large and, being large, it must be heavy andinassive so that it may not flex or quiver under the action of the hob. Now, by making this rat-her pon- Yderous element capable of being slid on the bed (through an agency such as will be described) it has the general characteristics of a sliiftable anvil and is, by its very massivecapable of absorbing the shocks largely independently of any means for clamping it to the bed. Furthermore, its great weight Nsu,

tends to hold it firmly on the ways of the bed and that weight acts in the same direction as the clan'ipingelements and hence the stanchion admits of being better and more rigidly secured to the bed bythe same y clamping force as a relativelythin carriage which naturally tenes to deflect and thus localize the clamping pressures. Also being large, the stanchion provides a base of ample dimensions and those proportions are adequate for the needs of a slidable element and do not have vto be enlarged; so that,` by eliminating the carnage and thus reducing the number of major elements of the machine, a saving of the equivalent vf'eight of metal may be accomplished and yet a more rigid construction attained. To slide the heavy stanchion, as will be perceived' hereinafter, this invention embodies a power traverse mechanism which enables the user to` perform that labor without effort; means for accomplishing that initial movement by manual power being also available for finer adjustments.

Fig. l is a side elevation of a hobbmgmachine showing a fixed Work-spindle and a shiftable stanchion supporting a head slidable thereon which carries a hob-spindle mounted at a major angle and adjustable plus and minus therefrom through a .minor incidental angle. Figs. 2 and 3 are rear and frontend-elevations of the machine. Fig. -l is skeleton of the transmission system and control levers for performing the various movements of the working and positioning Velements of the machine. Fig. 5 is a modification of the hob-mount. 6 is a sectional detail of a friction coupling between the prime-mover and a part of the transmission system. Fig. 7 is side elevation in detail of a portion of the interlocking control system for the quick traverse and feed for the hob-carrying head. Fig. 8 is a condensed fragmentary side-elevation of the means actuated by the cutter-slide for automatically operating the manually-operable levers for controlling the feed and the quick-traverse. Fig. 9 is a detail of the spring snap clutch for .throwing in and out the feed transmission. Fig. l0 is a detail of the spring-detent for urging the feed hand-lever into either one or the other of its alternative positions. Fig. 11 is an end-elevation of said levers. Fig. 12 is sectional-elevation, through line 12-12 of Fig. l showing an interlock for enabling the user manually to swing the main control lever from its stop to itsl start position; and showing also spring-operated means combined with means for releasing said interlock to enable said spring-'operated means to perform the operation of throwing said lever into its stop position.

The bed A, in this embodiment, is elongated and positioned horizontally and pro vides a forward working region in which the rwork-spindle is directly jonrnaled so as to occupy a lixedposition, and the bed providesalso a rear mechanisml supporting region on which the stanchion is slidably mounted. The Vworkspindle WT is shown journaled in fixed bearings A and it eX- thus giaing the work spindle a li.\;ed position at the toi-ward end ot the bed, it is at all times quickly accessible to the user and it is not at one time `further from the end of the bod than at another as oiiten happens -when the work spindle is shittable in position. The mountingv ot' the spindle is accompiislnwl in a very solid manner with the object ot realizing' the ellfect olf an anvil so that it virtually supports the work substantially as solidly as though it was clamped to the bed itself and, in consequence, the tendency to vibrate and chatter is reduced to a minimum.

The stanchion Si is in the nature ot' a heavy box-lile astinfr which is provided with slideways S and C2 at right angles to one another; the slideways S resting,T on the slideways S3 provided by the surface oit the bed and arranged to permit the heavystarn chion to be slid tmrards and away from the axis ot the work spindle tor the purpose ot determinine` the diameter ot the gear G to be cut by the machine. The purpose, otl the transverse slidew ys Si is to support and guide a head H which is thus shii'table in parallelism with the axis ot' the work-spindle so that the cutter or hob (which is carried by the head) may in the course of the 'feeding' movement cut the teeth ot' the gear (fi. .lt will be understood that this head lil is suitably `ailiibed to the slideivays Se and, in order to counterbalance the weicht ot the head H, a` eounterweight Ht may be arranged to rise and descend in an appropriate well provided by the stanchion S: conventional ropes and pulleys H2 and H3 being` provided as will be understood,

It is to be noted that the stanchion, being heavgv and massive, is in etiect a part oi. the solid bed itself because when clamped down to that bed, it becomes very solid therewith owingto the action oit the clamps augmented bv the weight ogt' the stanehion and by reason oli thc `tact that the base of the stanchion S very extensive so as to resist effectively such overturning forces as result from the pressure oit the hob against the work during the tooling operation. It will likewise be noted that the stanchion requires to be shiited only when a change is to be made in the, diameter ot the gears being' cut which ordinarily would be quite infrequent and it will also be noted that the shitting` ot the stanchion does not reduce the facility ot access ot the user to the work spindle and does not intcrpose obstructions when brought. closer to that spindle. Itwill also be noted that the slideivays S at the base of' the stanchion run to a region substantially underlying;l the head H so that this construction avoids the objectionable overhang which is necessitated whenever the work spindle is lnounted on a carriage which slides on the bed.

The transmission system for rotating both Lesaasi the work spindle and the hob, and it'or progressively feeding; the head H, and for shitting the position ot the stanchion S, and tor varying the `rates ot rotations and t'or Shifting the parts quickly .or slowly as the case may be, will now be described.

This transmission is in the nature ot a balanced drive and comprehends an intermediate splincd shaft X and two main transmission shafts Y and Z; shafl'ft Y being also splined. These two shafts are disposed at ri ght angles and the intermediate shaft is parallel with one oit them; the latter being in this embodiment the shaft that communi* cates motion to the work spindle. The intermediate shaft receives the power in the first instance; this being accomplished by the power line consisting oit a pulley orvother prime mover, a friction clutch the power shaft P and :appropriate `gears such, 'for example. as the two spur gears il)2 and P3 and the two angle gears P* and P5. The, splined transmission shaft Y is journaled in the shittable stanchion so as bodily to travel therewith and at its lower end is provided with an angle gear y/ which meshes With an angle gear a which is splined to the intermediate shaft Y.

The cutter C is mounted on a spindle c which is journaled in the head at a lixed major angle slopingeither to the right as shown by Fig. 3 or to the lett as shown by Fig'. il., but in order to provide vfor a slight plus Aand minus variation of `that major angle, the journals of the hob-spindle have a slight adjustment on the head H; as by means of bolts 100 and curved slots 101 struck about the aX-is 102 ot a worm 103. The minor angle adjustment will be, plus and minus. in the. neighborhood of tive dengi-ecs for a-single thread hob, and correspondinn'ly greater for a multiple-thread hob.

The inn'l'iediate drive comprises a wormwheel 104, the worm 108 and a (3o-axial bevel 105, and a bevel G splined to the vertical transmission shaf't Y; giving the ad instable right-angled Lt-,ireardrive shown by the drawings.

The lower horizontal non-splined transmission shaft Z is jourualcd in the bed of the machine and has a worm a atlixed thereto tor driving the worlespindle Vil through the wm'm-wheel VZ. The two pairs ot change `Jyears :r2 and .22, -and 10T and 108, establish the driving relation between the intermediate power shaft, X and the tra nsmiesion sha l t, Z: it being' observed that this arrainrement provides a balanced drive in which the six nears 1W, z, 22, 108. 107 and m2 transmit vthe motion to the work spindle. and likewise six fears 104;, 103, 105, 10G, {1/ and .'L" transmit the motion to the cutter. Further detailswill be described in connection with an explanation ot the manipulations of the machine.

The controls for the hobber, vvill noW be explained. These'provide for preliminary adjustments such as setting the hobvat the required distance from the axis of the Work to cut a helical-gear of the desired diameter, and also for readily getting the hob close to the end of the blank so that it Will not have to travel far, after the Whole correlated system is set and started in its fixed ratios of movements, before the hob comes into engagement With the blank and begins its cutting operation.

Once the actual tooling operation is in progress, no independent cessation, variation or reversal of any of the movements should be made for, so long any part of the cutter is in the blank, any departure from the correlated ratios would mutilate the helical gear in process of' formation. But occasion may arise for suspending the cutting operation and provision for this is accomplished through a control for expeditiously stopping or starting the entire system of movements without in any manner affecting the predetermined correlation of ratios.

Then the ho-b has run through the blank, and is entirely clear thereof, itsk travel must in due time be arrested; otherwise'damage to the machine would result. The machine, at that particular' time, may not be under the close observation of the user and, to safeguard it against accident, there is provided an automatic stop for discontinuing further travel of the cutter-head, but only after there is no possibility of any interference between the hob and the gear.

AAfter the hob has complete-d its Work, and

after the finished helical gear has been removed from the Work-spindle, it is desirable to return the hob to its start-ing point Without undue loss of time, and a quick return control is provided for this purpose. The user may thenv insert a fresh blank and set the mechanism again in operation to repeat the cycle.

To manually shift the stanchion a handivhcel Y (provided with graduations or micrometer adjustments) is affixed to a shaft that. carries an angle gear V which meshes with an angle gear V2 which iu turn is spiined to the screuv S which runs through the fixed nut N and causes the 'screw to translate bodily; this translation being communicated to` the stanchion by means of an appropriate lug or part S4 journaled to the screw. This manual means enables the user veryreadily to bring` the stanchion to any desired position with respect to the Workspindle for cutting helical gears of predetermined diameters.

To sta-rt the machinethe power lever B is actuated. This shifts the collar 8 and slides a long kev 9 (which is translatably countersunk in the shaft P) and this key actuates a friction clutch (not shown) between the prime mover P and the shaft P. The transmission elements previously described are then maintained in motion by the power, and the cutter and the Work are both revolved and fed at the co-relative rates determined by the tivo change gears e2, 108, 107 and m2. A characteristic'of the arrangement of this lever is that it is uni-directional yin manipulation, i. e., it may be moved by hand to start the machine but, when so moved, it is held by a Vcatch against being manually shifted back again, so that, to stop the machine, the starting lever must be released from the hook by means to be later referred to.

So muchof the transmission system as constitutes the balanced drive for the two spindles has been described. The motion for feeding the hob isv conveyed by a transmission consisting of an angle gear 1 mounted on the shaft Z and meshing with an angle gear 2 affixed to the shaft 3. A Worm 1 on that shaft drives a Worm-Wheel 5 which turns the shaft 6 and (through appropriate change-gears designated generally by 7) the gear r2 is Vdriven and this gear is aced to a sleeve 'i' which is loosely mounted on the Shaft F which conveys the motion for feeding the cutter-head. The clutch teeth r are maintained-in engagement so long as the hob is in the blank, but they may be disconnected 95 to permit. the shaft FG to be driven by other means when the hob is to be shifted down` into proximity With the blank or shifted up past the removed blank into its initial position to start on the next cycle, as will be ex- OU plained later.

Angle gears F5 and Ff transmit the motion of the shaft FG to the shaft F3 Which is journaled in the` stanchion and, at its upper end, has a gear F2 Whichmeshes with a gear 105 F which is a unit with a nut that turns about the non-rotatable feed-screw F. That feed-screw is affixed to the head H and is causedto move up or down, as the case may be, by the rotating nut. In this manner, the 110 hob journaled on the head H is caused to feed dowim'ardly Whenever the hob in the blank and the'parts are connected de scribed, or caused `to make a quick traverse either up or down when the hob is clear of U5 the blank and the parts are differently connected, as Will be described.

To stop the entire machine, either manually or through an automatic trip, the hook 112 must be depressed. To do this manu- 120 ally, the lever 109 must be operated; said lever 109 serving to release the catch and en able the lever B to return and the master'- clutch to open througha quick-acting spring action. Referring to Fig. 12, there Will be 125 seen an arm 110 extending from the pivotshaft 111 of starting-lever B. The extremity of said arm 110 over-rides a depressible hook 112 (see also Fig. 4) which is keyed to a rock-shaft 113 extending along-side the 130 machine and splined to a bell-crank lever lll; the one arin 109 ol which is operable manually, and the other arm 115 of which is operated automatically by certain trip mechanism :-in each case to stop the entire inachine. il. spring-pressed plunger 116 normally holds up the hook 112 but permits its dein'ession as described. When thus depressed. the catch is released and the arm becomes tree to swingl and the starting lever ll can now move into its stop position; this beine' done by the pressure ol" a spring'- prcssed plunger 11T which acts against an other arm 11S also extending' Alroin the pivotshalt lll, with the result that the collar 8 shifted on the main power shai''t P to open the master-clutch.

'lhe transmission which is utilized to drive the shaft if at a qi1iclt1ave1se rate (in lieu ol' the slowrdrivine gear r2) when it is desired to accomplish a preparatoiw`- shift ot the hob*carryingl head, is as follows: Fast to the pulley l is a gear Q. which permanently meshes with a `e'ear Q which is 't'rictionally c n1nected through the leather 'lacinpgs 17 and iS (see Fie'. (S) ot' the clamp disks 19 and 2l) with the shalt F; a nut 21 serving to determine the amount ot' the friction. ln this manner. the sha'lt QF is driven simultaneously with. but impositively by, the pulley l so that slippage may occur and breakaee prevented in case the head be brought against some obstacle. Gn the end of the shal't tl is a bevel gear Q3 which perinaneutly meshes with right and lett bevel gears Q. and QI which are loosely mounted on the sha'lt FG. A clutch Q9 is splined to the shaft ll.l and when shifted to the one side or the other. will cause that shaft to be rotated either one way or the other; or not at all if the clutch Q. be in neutral position. The position ot the clutch is determined by a linger e projecting from a lever on the rocl- .shalt Z which. through the bevel gears c and c. actuated by the rocleshalt 7) which in turn is rocked by the hand-lever a.

rlo shitt quickly down the cutter head, the lever it nmst be moved down into the lower dotted position shown by Fie'. 1l. Betere this can be done. the block pin (7 .must be pulled against its spring` out oil` the path ot that lever. This temporary obstruction is precautionary so that the user will be obliged deliberately to perform an extra operation to bring the head down rapidly; otherwise he might ina dvert-entlypress down the lever fr and cause the cutter to be brought down rapidly into the work and broken. lFrom what has been said heretofore, it will be seen that this deinfession of the lever a connects the shatt FG with a high speed transmission and, since that shaft must also be connected with a low-speed or cfeed7 transmission to produce the correlated ratios used whenever the hob is in the work. it is essential that the one shall be out betere the other can come in and conversely. This sateguardingr is accomplished by the interlock shown by Fig. 1l in which the rockshatt m that controls the connection (by shitting` the gear r2 ot the slow motion t ansmission, has an arm 71:2 in'ovided with al V- shaped linger j" which (when the 'leed is on) enters a central recess in the ledge fr of the lever a.. "ilflhen` however, the lever a. is not in its neutral position, the .linger f will. by reason ot' its double slope, be forced out ol the recess and caused to ride on the higher portions o'l the ledge u? and this can only happen when the tetdlever is in the dotted position indicated by Fig. 11.

'lhe means whereby the rock-shaft `1n determines the en {aneinenl"` and disent, ae ment of the clutch teeth r shown best by Figs. a and l). il. shifter arm y) acts to bodily shi'lt the sleeve r lo establish or disconnect the parts described; this shiliter arm being loosely mounted ou the shaft 0. A yieldable detent p acts on the shitter pin so as to urge the parts into clutching relation; the purpose being; to provide a quick yet not too positive an action. Bevel gears n and a connect the shaft o with a rockshatt ne. and a handwlever L permits the roclesha'tt fm, to be moved manually. On this rock-shatt 11n, is a small arm Am. which has a spring-pressed pawl cooperatingwith an oscillatable pawl in?. The latter. by moving,a against either the stop-pin 23 or the stoppin 2l, will resiliently deter niine the position ot the rock-shatt fm, and this motion will be correspondingrly imparted to the rocleshalt 0, which carries the part p3 provided with the a'loresaid yield- .ine detent p to throw the sleeve clutch r impositively into operative position and provided also with the lug' yf" to throw it positively out. Thus it will he seen that when clutch Q is in either its right or its lett engaging position. clutch 1" is discolniected. and when clutch is engaged, clutch Q can be only in its neutral noir-transmitting position. Therefore. by pulling out pin g and b v depressine` the lever a, the Jfeed is disconnected and the quick traverse is accomplished and the head l'l moves down rapidly.

"l`o shilt quickly and upwardly the cutter head. the lever (r raised to the upper dotted position shown by Fig. l1. The interlock again insures that the leed will be out so that when the clutch Q. is moved into its motion reversing; posit-ion, the transmission will take place through the quick traverse means and the head will go up rapidly.

To adjust the limits ol the quick traverste travel ol the cutter head. this invention provides a shift-rod T pivoted to the tree end of an arm a extending to the right (as shown by Fig. 1l) 'trom the pivot of the.

till

fil)

hand-lever a so that, when lever a is depressed, the shift-rod T will rise, and conversely. Hence if said rod T be pushed down, the effect will be the same on the control mechanism as if the n'ser had pulled up the hand-lever a.

Now, adjustably bolted (by slot 10 and bolts 11) to the cutter-head H is a camplate D. This has an inclined face 12 and within the path of travel of that face will be (when the quick down traverse is on) the finger 16 on the end of the lower arm of a bell-crank lever E which has a fixed pivot at 15. The shift-rod T is pivoted at its upper end 14 to the other arm of that bellcrank Jever. Hence, when the shift-rod is raised (to produce a quick down-traverse) the finger 16 will be in the path of the camplate D. If now the cutter-head descends, the inclined face Will in due time contact with the finger 16 and depress the shift-rod T; thus raising the hand-lever a.

But this automatic raising of the handlever a (corresponding to a depressiony of the shift rod T) will cease as soon as the inclined face 12 haspassed the finger on the bell-crank lever E. It is to be noted that the extent of this movement is such lhat, when the linger is coincident with the .iat non-sloping face 3 of the cam-plate D,

eiland-lever a is in its mid-position as own in full lines by Fig. 11. Hence the etent fof the feed handdever 7s will now be able when actuated by the user) to enter the notch in the surface. a2 and the downfeed of the cutter-'head will be substituted for the down quick-traverse. The cutter is new about to enter the work at a feed rate only and cut the gear-teeth. Tf now the user should try, through a mistake, to push down the hand-lever a, he would be prevented by the finger 16 which is now riding along the non-sloping face 13. Therefore, the down quick-traverse is limited (by adjusting the initial position of the cam plate and the user cannot commit the error of causing the cutter to enter the work at any rate faster than that of the normal feed To adjust the limit of the upward quicktraverse. the collar or dog T2 is set at the appropriate point on the rod T so that the projection H (affixed to the cutter-head) will engage said collar and move the traverse red T upwardly and thereby depress the hand-lever a from its raised into its neutral jwsitien. This will stop the travel of the cntter-head H because the detent shown by Fig. 1() will hold the hand-lever 7c in the dotted line position shown by Fig. 11 until it is actuatedv by hand.

To limit vthe extent of feed, there is an adjustable collar 33 on the feed shift-rod 8e which controls the position of the hand-lever 109 as Will be understood. Also, asa'matin fs ter of precaution, collars T', 36 and 37 are permanently aliixed to the respective rods T and 34 to prevent the user from making any adjustments beyond the maximum scope of travel provided kfor the cutter head H.

The shift-red 84, being pivoted to the arm 115, will turn the shaft 113 counter-clockwise, as `viewed by Fig. 12, whenever the projection H on the descending head H meets and pushes down the collar This will release the catch 112 and permit the spring-plunger 117 to snap open the master clutch in the main pulley lD and thus stop the entire machine: excepting of course the auxiliary quick-traverse line from Q to the reverse gears Qtand Q5 Whichidle with the prime-mover P. The user will, of course, so adjust the collar 33 on the shift-rod 34 that the hob Will have fed entirely clear of the blank before the correlated drive-system is automatically stopped 'as described.

' The attendant, upon the conclnsion of the eut,.will remove the blank from the stopped work-spindle. Upon lifting the lever a and clutching the then-idling gear Q5 to the then-still shaft F6, the cutter-head will rise quickly to its initial position until arrested by the push Vof the projection H against the collar T2. The attendant can then mount a fresh blank on the then-still work-spindle. Upon depressing the handle a, the hob will be moved quickly towards and stopped (by vthe cam D) near the upper' end of the blank.

The lever B is then operated to close the master-clutch and the handle is then actuated to engage the clutch teeth r and. the correlation of ratios essential to the helical effect is thereby established, and the hob thereupon proceeds to enter the blank and cutthe helix.

ldithout further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various utilizations by retaining one or more of the features that from the standpoint of the prior art, fairly constitute essential characteristics of either the generic or specific aspects of this invention, and, therefore, such adaptations should be, and are intended to be, comprehended within the meaning and range of equivalency of the following claims.

Having thus revealed this invention, I claim as new and desire to secure the following comhinations and elements, or equivalents thereof, by. Letters Patent of the United 1. A balanced-drive hobbing-machine comprising a bed; a relatively heavy stanchion shiftably supported thereon; a work-snpporting spindle non-shiftably journaled in said bed nea-r one end thereof; an intermediate splined shaftand a parallel transmission shaft, each journaled on said bed transversely to said spindleg'two pairs of spur chaiuge-gears connectingsaid two shatts; a splined transmission shaft journaled on said stanchion parallel with said spindle; a head slidable on said stanchion; a hob-supjziorting spindle on said head, said holnspindle being` inclined at a major angle oit about a third to an eighth of a quadrant; means tor eililecting a minor adjustment ot a icw degrees ot said major angle; two pairs ot angie-gears connectinpl said liolrspiiitlle with said splined transmission shaft, one of said angle-gears beinel splined to said sha'tt; a pair oi: anglegears connectingv said sliaitt to said intcrnaaliatc shaft, one ot said gears` beine' splined to said intermediate sha'tt; a nd a pair ot angle gears connecting said parallel transmission shaft with said non-shittable work-spindle.

2. ii. lailanced-drive hobbinganachine com binine; a bed; a worlosupporting` spindle oecupjf'ing a. tixed position on said bed; a heavy; stanchion shittalilj7 mounted on said bed; a hob-sluiporting spindle slidably carried by said stanchionl` said spindle being set at an angle restricted to about a third to an eight oft' a quadrant; a transmission connectinr said spindles and consisting ot not more than one intermediate and two tranniission shafts, said intermediate shatt being splined and arranged parallel to the work-driving transmision shatt and transversely to the holidrivingj transmission shaft: the adja cent ends ot said two parallel shaitts being directljv connected b v two pairs o'l changegears ot' the spur-tooth type, the hob-driving` sha'tt beingl splined; an anglegear slidable on said intermediate shaft; said hob-driving shaft being `geared at one end to said spindle through tour angle-gears and at its other end geared directlj1 to said slidable angle-gear` a prime-mover geared direetljv to the inter mediate sha'tt wherebj7 the power for driving said spindles will be derived from the respective ends thereof: and means Jior eitecting` a progressive relative translation between said spindles in a direction parallel with the woi'losupporting spindle.

3. t liobbing-nnichine combining1 a hobspiiidle; a \\'orl -s] )in lle: a prime-mover; a transmission having` balanced six-gear branches, the one tor driving;- the hobspindle, and the other lor dri ring' the workspindle; and means 'for mounting ttor said hob-spindle at a major angle ot' about a third to an eighth ot a quadrant. said means providing a minor adjustment Jfor increasing' or decreasingy said major angle within about tire degrees.

Lt. it hobber tor `generationr various helicaltrcars haring; a common helix angle, said hobbcr combiningT a lmb-spindle: an angularly arranged mount tor initialljv holding` said hobfsi'iindle at a base-angle corresponding' to said common helix angle: means for enabling said mount to be swung' through an incidental angle sutlioient to compensate tor the helix anale ot the hob carried by the hob-spimllei` a \\'orlrspindle: and a trans mission system tor simultaneously rotating' each ot said spindles and tianslatingl said hob spindle, said transmission system being ratioed to correlate said three component motions to `generate a gear havingr;l the a'ioresaid common helix angle.

5. it bobbing-machine combining` a hobspindle; a worl-sj'iindle: a pi'infieanover; a transmission havingbalanced six-gear branches, the one tor driving the hobspindle` and the other tor driving' the workspindlc: and meansI 'tor mounting 'tor said hob-spindle at a delinite major angle ot about a third or an eigrhth olf a quadrant, said means n'o\'idinfr a restricted minor adjustment .tor inereasinal or decreasingi said major angle bj a 'tcw degrees only.

(i. :i bobbing-machine combining a hobspindle; a work-spindle: a prime-mover; a transmission haring' balanced six-gear branches. the one tor drivingr the hobspindle, and the other tor driving' the work-A spindle; n'ieans tor mountingr it'or said hobspindle at a detinite inajorangjle of, about a third or an eighth ot a quadrant` said means providing' a restricted minor adjustment for increasing or decreasine` said major angle b v a 'lew degrees only; a shiitable stanchion siipporting;l said means: and a non-shit'table sujniort tor the work-spindle.

T. It liobhing-machine comprising a hobspindle and a work-spindle; a transmission having* balanced branches tor driving said respective spindles; restricted means tor mountingl said hob-spindle at a substantially fixed angle not greater than about a third or less than about an eighth ot a quadrant; a shittable stanchion supporting said n'ieans; and a non-shiitable support tor the workspindle.

S. A helical-gear, hobber combininibj` a prit-spindle; a hob-spindle set at a major angle thereto rcpresentinel the helix angle ot the heli al gear to be cnt: a short sha-tty transverse to one end ot the hob-spindle; a pair ot anale Q;ears directly comicctinn' said shalt with said spindle; an elongated transmission shatt parallel with said work spindle: a secoinl pair oi angle-gears directljv connecting said two shafts: and bean ing means ior said spindle, said means beine,n arra'ularlv adjustable about said short shait as an axis, wherein' said hob spindle may be swung through a small incidental angle to moditv said major angle to the extent ot coinpcnsatinpr t'or the helix angle o't the hob.

9. A helical-gear hobbcr combiningl` a work-spindle; a hob-spindle at a major anale thereto represeiiting.;` the helix angle ot the helical gear to be cut; a short shaftJ transverse to one end oi the hob-spindle; a

till

Worm and Worm-wheel directly connecting said shaft with said spindle; an elongated transmission shaft parallel With said Work spindle; a second pair of angle-gears directly connecting said tWo shafts; and bearing means for said spindle, said means having a sufficient range of angular adjustment about said short shaft as an axis; to enable said hob spindle with its Worm-Wheel to be swung through a small incidental angle to compensate for the helix angle of the hob.

10. A hobbing machine adapted to gen-F erate helical-gears combining a Work-spindle; a hob-spindle adapted to operate at a major angle thereto representing the helix angle of the helical gear to be cut; a Wormwheel affixed to one end of said spindle; a short shaft extending transversely from said end of the hob-spindle; a Worm on said shaft directly gearing it with said spindle; an elongated splined transmission shaft parallel with said work spindle; a

second pair of angle-gears directly con-y necting said two shafts, one of said gears being' slidable on said splined shaft; angularly-adjustable bearing-means for enabling said spindle with its worin-Wheel to be bodily swung about said short shaft as an axis through a small incidental angle sufficient to compensate for the helix angleof the hob; a second transmission shaft; a pair of angle-gears connecting it to the Work-spindle; an intermediate shaft; a pair of angle-gears connecting it With said first transmission shaft; means for bodily translating the hob-spindle; and change-gears between said intermediate shaft and said second transmission shaft for correlating the three component motions of the hob and Work spindles to produce. the helical effect.

11. A hobber for generating helicalgears combining a Work-spindle; a hobspindle adapted to operate at a magor angle thereto representing the helix angle of the helical gear to be cut; a first and a second Worm-Wheel affixed respectively to said spindles; a short s shaft extending transverse from one end of the hob-spindle; a Worm affixed to said shaft in mesh with the Worin-wheel on said hob-spindle for directly gearing said shaft to said spindle; angularly adjustable bearing-means for enabling said spindle with its Worm-Wheel to be bodily swung about said short shaft as.

an axis through a small incidental angle to modify said major angle to the extent of compensating for the helix-angle of the hob; a balanced drive for relatively rotating said spindles through said Worm-` Wheels; and means for feeding one of said spindles.

12. A hobber combining a Work-spindle; a hob-spindle.; a slidable head for oneof said. spindles; a transmission forv correlatslidable head therefor; a work-spindle; a

drive-system comprising a transmission eX- tending from the one spindle to the other for establishing the rotational ratio therebetween; `a branch transmission for sliding said head; a first means for positively relating Vsaid branchV transmission to said spindle-driving transmission to correlate definitely the feed of the head With the A' rotations of the spindles to realize the helical effect; a second means interchangeably available for more rapidly driving said branch ytransmission to cause a quick-traverse of said head; a control system for automatically rendering said second means impotent to traverse said head in the portion of its path utilized during the actual hobbing action.

14. A hobber combining a hob-spindle; a slidable head therefor; a Work-spindle; a drive-system comprising a transmission extending from the onespindle to the other for establishing the rotational ratio therebetween; a branch transmission for sliding said head; positive means for relating said branch transmission to said spindle-driving transmission to correlate definitely the feed of the head with the rotations of the spindles to realize the helical effect; an impositive means interchangeably available for more rapidly driving said branch transmission to cause a quick-traverse of said head; a control system for automatically rendering said impositive means impotent to traverse said head in the portion of its path utilized during the actual hobbing action; and an interlock for prohibitingthe utilizationr of said positive means While said impositive means is potent.

15. A hobber combining a hob-spindle; a slidable head therefor; a Work-spindle; a drive-system comprising a transmission extending from the one spindle to the other fory establishingy the rotational ratio therebetween; a branch transmission for sliding said head; a first meansfor positively relating said branch transmission to said spindle-driving transmission to correlateV definitely the feed of the head With .the rotations of the spindles to realize the helical effect; a second means interchangeably available for more rapidly driving said. branch transmission to cause a quick-trair` erse of saidhead; an interlock control syslil teni for automatically renderingl said lirst ineans impotent to l'eed said head when said second means is setr in action, and tor permitting saidl first ineans to be utilized when said second is out; and an independent trip nieehansiny for automatically disconnecting said transi'nission troni the source ot motion when said head has carried the hob through the blank;

16. A liobber combining a worli-sl'iindle; a hob-spindle; a slidable head toe one ot said spindles; a transmission tor correlating the rotations oit each spindle with the sliddetermined helical elliect; a prinieanorer; a clutch;r a handderer adapted to render said clutch -eli'ective lo drive said transmis sion; a latch tor preventing said hand-lever troni being nianualli-Y actuated lo discontinue saidildrive; asecond hand-lever; and inechanisin tor enabling it to release said latch and rendersaid clutch ineffective;

lT; Ar hobber combining' a work-spindle; a hob-spindle' said spindles; a transmission l'or correlatinigv the rotations ot each spindle ivith the sliding relation therelntireen to realize a pre-` determined helical el'l'ect; a prinie-niover; a.

clutch; resilient nieans urging said clutch" open: aY lever adapted to be operated inaniially to overeonie said resilient ineaiis to render said clutch eli'eetive, to drive said transmission; latch nieans 'tor preventing said hand-lever troni swinging reversel37 to diacoiitiiine said drii'e: a second hand-lever;

and inechanisin tor enabling` it toi'ender said liitrliiii eaiis ineti'ective and thereby permit said resilientiiieans to open said cluteli.

in. AL liobber coinbininpI a \vorli-spindle; a hob-spindle; a slidable head tor one ot: said spindles: a transmission tor correlating the rotations oli eaclitspindle with the slid# ingli'elation therebetween to realize a pre determined heli al ett'eet; a priine-niovergia clutch; resilient iiieans urging;v said clutch open; a latcledcvire :tor holding` said nieans ina position such that said clutch is closed; and altrip inechanisin operated b y said slidable head for releasingsaid .latch-device to pei-init said ineans to open said rlutcli.

111A, liobber combiningv a hob-spindle; a slidable head therefor: a work-spindle; a transmission extendingT troni the one spinb dle to` the other` 'lor establishing the rotational ratio tlierebetiieen: a priiiie.-inover: a rluteli for connectingl it to said transmission; avliianrh transmission toi' sliding' said head; a` first ineans ior positii'elil relating said branch transmission to said spindle-driving transmission to correlate definitely the feed oi` the head with the rotations ot the spindies to realize the helical ell'ecl; a second means intercliangeablif` available ttor more l rapidly` driving said branch transmission to ing relation therebetween to realize a" pref a slid-able head for one ot Lenmar eauee a quick-traversre ol`i said head; an interlock control` system 'for automaticalli1 rendern@l said Iirst ineans iiiipotent to teed said head when said second nieans is set in action, and l'or perinittinpI said iii-st iiieann to be utilized ivhen said second out; a lirst trip ineehaiiisni loi' renderingl said second nieans inellective before aaid` branch transniission has carried said head into the hobbing region; andy an independent trip ineehanisni .tor antoinaticall \v (fliseonnfnrting said rluteh when Isaid head has rarried the hob through the blank.

20. t hoblier eonibiiiinej a` hob-spindle; a slidable head therefor; a work-Spindle; a drive-sysleiii comprising; a lransniis-E.ion extending :troni the one spindle to the other for establishiiig` the rotational ratio therebetween; a i'niine-niover; a lirst clutch tor connecting it with said drive-system; a. branch lraiisniisaioii igor sliding;` said head;

a second clinch i'or positively relating),` said branch transmission lo said drive-systeni to correlatedeliniteli' the heed ol' theheadfirith.

the rotations ot the si'iindles to realize tho helical eii'eet; a reversing clutch; ineans continuously driven by said priine-inorer adapted to be eonnerted through Isaid third Clutch with said braiirh transmission to cause a ipliek-traverse ol said head; a trip nierlianisin operated h v said slidable head Alor so (-iiiiti'fill-iiigv said ri-iversing' clutch that it can rause the head lo descend onl)r when the hob is out oi eonlact with the blank, said trip nieehanisin being; adapted to open said lirst eliiteli at the roncluaion olf the holil'iing operation; and an interlock YIgor openingr said serond clutch whenever said reu versing clutch is-closed.

2l. A lielicalpea r liobbei eoinhininp,r a rotatable liob-spii'idle; a rotatable work-spin die; afteedable head loi' one ot said spindles; a general transmission positively actuating said parts sinniltai'ieonsljv at rates correlated to rield a helical atleet; a, prime-mover; a niaster friction-elntehg means operable either autoiiiaticallir by said head or inaiiually tor openiniai` said lrietioii-chitehg and a liaiidlever li'or closing;` said 'liiction-clutch to cause said prinie-n'iover iniposilivelyT to drive said general transmission.

QQ. A lielical-gear liobber, combining a rotatable liolrspindle; a rotatable WorkA spindle; a teedable head :tor one ot said spindles; a general transnii'ssion posit-iveliT actuating saidlparts sinniltaneonsl)7 at rates correlated to yield a helieal etleet; a primen mover; a master 4liiotioircliilehg tivo handi levers, the `first for closing; andthe second for opening` said triction-ehiteh; and a connection 'for enabling said nt'eedablehead atfapredetermined station to operate said. second lever automatically.

i3. A helical-gear hobber combining' a hob-spindleg a Worlespindle; a normally llt) ion

... .irl

idling but continuously-driven transmission terminating in a reversing mechanism; a general transmission for relatively rotating and feeding the spindles at rates correlated to produce a helical effect; a positive-clutch in said general transmission for discontinuing the feeding action thereof; a primemover; a friction-clutch; a hand-lever for closing said friction clutch to connect said prime-mover with said general transmission; another lever operable manually and automatically to disconnect said frictionclutch; and a third-lever adapted first to open said positive-clutch and then to render said reversing-mechanism operable to transmit motion from said continuously-driven mechanism in either direction.

24. A helical-gear hobber combining a pair of spindles; a feedable-head for one of said spindles; a transmission extending continuously from the one to the other for permanently maintaining the rotational ratio predetermined by a preliminary setting; and having a branch-transmission leading to said head; a positive-clutch for isolating said branch-transmission from said first transmission; a fast-running transmission; a motion-reverser for disconnecting or connecting the latter with the branch-line transmission; a lever shiftabl-e to occupy either one of three positions to control said motionreverser; a second lever for controlling said positive-clutch; a master friction-clutch; a third lever for closing said master frictionclutch; a fourth lever for opening said friction-clutch; and mechanism adapted to be actuated by said feedable head for operating said fourth lever automatically.

25. A helical gear hobber combining` a work-spindle; hob-spindle; a mountingconstructed to lsupport said hob-spindle at a major angle corresponding to the helix angle of the gear to be cut; but tiltable sufficiently to afford an incidental angular adjustment of the hob spindle to compensate for the helical angle of the hob cutter; a splined shaft arranged transversely to the hob spindle and parallel to the work spindle; gears connecting said splined shaft and hob spindle and adaptable to said extent of adjustment; a prime mover geared to said splined shaft; a transmission shaft geared to said work spindle; means to translate said hob spindle bodily parallel with said work spindle; and change gears between said prime mover and transmission shaft for correlating the three component motions of said hob and work spindle to produce a gear whose helical angle corresponds with the major angle of the hob spindle.

26. A helical liobber combining a continuously running prime-mover; a main transmission system; a inaster-clutch therebetween; work andfhob spindles adapted to be co-relatively rotated and translated by said system; an auxiliary transmission continuously driven by said prime-mover independently of said master-clutch; and control means enabling said auxiliary transmission to accomplish a rapid relative translation between said spindles when said main transmission systein is ineffective to eiIect its translation between said spindles.

27. A helical hobber combining two spindles rotatable and translatable relatively; means connectable therewith for accomplishing said translation rapidly; a lever adapted when moved in a given direction so to connect said means as to enable it to translate one of said spindles rapidly in said direction; a trip for automatically disengaging said means at a predetermined station in the advance of said translation;

means connectable for slowly continuing said translation; manual means for reversing the direction of said translation; and an interlock for substituting said ii'rst-mentioned for said second-mentioned means when said reversing means has been resorted to.

In witness whereof, I have hereunto subscribed my name.

WILLIAM F. ZIMMERMANN. 

